encode

# File activesupport/lib/active_support/json/encoding.rb, line 74
        def encode(value, options = nil)
          options = {} unless Hash === options
          seen = (options[:seen] ||= [])
          raise CircularReferenceError, 'object references itself' if seen.include?(value)
          seen << value
          value.to_json(options)
        ensure
          seen.pop
        end